Which would you rather have happen when you get old?
1) Good mind, bad body. You are coherent and can hold conversations as an old fart, but your body is so brittle and uncontrollable you suffer just getting in and out of bed at night. You also can't control your bladder and are required to wear depends.
or
2) Good body, bad mind. You are overall in good shape physically. You can move around without a walker/cane/wheelchair. Your mind however is gone. You have Alzheimer's or the likes. People think you're crazy.